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Background/objectives: Sarcopenia defined by the association of skeletal muscle mass depletion and a decreased physical performance is underdiagnosed in chronic obstructive pulmonary disease (COPD) patients. The objective was to assess prevalence of sarcopenia and malnutrition in hospitalized COPD patients during an acute exacerbation, after 6 months follow-up and the 1-year survival.Subjects/methods: Hospitalized COPD patients were recruited for the assessment of body composition, handgrip strength, respiratory function, and maximal inspiratory and expiratory pressures (MIP and MEP), during hospitalization and 6 months later. Sarcopenia was defined according to the criteria of the European Working Group on Sarcopenia in Older Adults, malnutrition was defined according to French criteria 2007. Survival data were collected 12 months after hospitalization.Results: We analyzed data from 54 patients, aged 68 ± 9 years and BMI 26.9 ± 7.8 kg/m2, with an average FEV1 of 1.13 ± 0.49 l (45 ± 16% predicted value). Sarcopenia and malnutrition prevalence were, respectively, 48% and 52% during hospitalization, 30% and 30% after 6 months. MIP and MEP were lower in sarcopenic patients (p = 0.01 and 0.009, respectively). In multivariate analysis, skeletal muscle mass index and MIP were positively correlated at 6 months' follow-up (r = 0.40, p = 0.04). The 1-year survival rate was lower in sarcopenic patients (65 vs 86%, p = 0.03), particularly when malnutrition was associated (p = 0.02).Conclusions: Sarcopenia in COPD patients is highly prevalent during and after recovery of an acute exacerbation, exposing to lower survival. A multimodal management is required to treat sarcopenia and improve prognosis. [ABSTRACT FROM AUTHOR]

The determination of the insulin like growth factor I (IGF-I) concentration in the interstitial milieu is of outstanding importance to explore its autocrine/paracrine function. We previously reported a method to calibrate microdialysis probes for lactate and glucose (slope method). In the present study, we investigated the ability of our method to determine the concentration of larger molecules, such as IGF-I. We observed in vitro a close linear relationship (r = 0.86, P < 0.0005) between the recoveries of lactate (RecLac) and of IGF-I (RecIGF-I), giving access to the measurement of IGF-I with the same accuracy as the one previously found for lactate and glucose. In seven human volunteers, we calibrated each probe with the slope method: we first determined in vivo for every probe the specific RecLac/loss ethanol relationship and thereafter, using that relationship, we deduced RecLac from the loss ethanol value measured in every dialysate. This allowed calculation of RecIGF-I from the calculated RecLac value and the in vitro RecLac/RecIGF-I relationship, and finally free IGF-I concentration in muscle interstitial fluid. The mean free IGF-I interstitial concentration was 6.8 +/- 3.2 ng/ml while the mean plasma concentration was 0.4 +/- 0.2 ng/ml. This large gradient from interstitium to plasma for free IGF-I could be related to the local action of this growth factor. [ABSTRACT FROM AUTHOR]

Microdialysis presents the unique possibility to measure metabolite concentrations in human interstitial fluid. During exercise, the recovery of these metabolites should be precisely monitored since it is known to increase greatly with muscle blood flow. The loss of ethanol, perfused at low concentration, can be accurately measured and reflects the changes in dialysis conditions. We evaluated whether using the relationship determined in resting metabolic conditions between the loss of ethanol, as reference substance, and the recovery for lactate or glucose would allow us to calculate precisely the concentration of these substances and their variations during exercise. Using the new catheter calibration method (slope method), the error of estimation of lactate and glucose in vitro was limited to -0.6 (5.8)% and -0.7 (6.2)%, respectively. In resting human muscle, the slope method proved to be as accurate as an established calibration technique ("no net flux method") to evaluate interstitial lactate concentration [1.82 (0.58) vs 1.83 (0.47) mM, respectively]. During dynamic knee-extension exercise or light neuromuscular electrical stimulation, the estimated interstitial lactate and glucose concentrations varied differently, but their time course changes remained consistent with their respective plasma values. We conclude that, after an initial calibration step, the slope method allows accurate measurement of interstitial muscle metabolites and it could be used to monitor rapid metabolic changes during exercise. [ABSTRACT FROM AUTHOR]

There is a growing need to measure arterial oxygen saturation with a non-invasive method during heavy exercise under severe hypoxic conditions. Although the accuracy of pulse oximetry has been challenged by several authors, it has not been done under extreme conditions. The purpose of this study was to evaluate the accuracy of a pulse oximeter (Satlite, Datex, Finland) during exercise under hypoxic conditions where arterial oxygen saturation was below 75%, simulating exercise at extreme altitude. Ten healthy non-smoking men performed two exercise studies of 30 min under normoxia and under hypoxia on two consecutive days. The exercise intensity was 80% of maximal O2 consumption of O2max. Arterial oxygen saturation measured by pulse oximetry was corrected ( SpO2[corr]) according to previously published equations and was compared to arterial oxygen saturation ( SaO2) in blood samples taken simultaneously from the radial artery. Reference arterial saturation values ranged from 57.2 to 97.6% for the whole data set. This data set was split according to low ( SaO2 ≤ 75%) and high ( SaO2 > 75%) SaO2 values. The error of pulse oximetry ( SpO2[corr]− SaO2) was 2.05 (0.87)% [mean (SD)] and 1.80 (1.81)% for high and low SaO2 values, respectively. SpO2[corr] and SaO2 were highly correlated ( r = 0.93, SEE = 1.8) for low values. During high-intensity constant workload under severe hypoxic conditions, once corrected, pulse oximetry provides an estimate of SaO2 with a mean error of 2%. Thus, the correction previously described for SpO2 values above 75% saturation applies also to SpO2 values in the range of 57–75% during exercise under hypoxic conditions. [ABSTRACT FROM AUTHOR]